The purpose of the research is to gain an understanding of the mechanism of self-assembly of microtubules and factors which control the formation and depolymerization of these structures. Experiments are designed to study the kinetics and thermodynamics of the self-assembly process of pure tubulin including both the initiation and elongation processes and to examine the role of associated proteins in the reaction. We are also studying the role that sufhydryl and disulfide groups play in the assembly process. Specific modifying agents are being used.